An opening or gap is purposely provided between adjacent concrete structures for accommodating dimensional changes within the gap occurring as expansion and contraction due to temperature changes, changes in concrete structure dimensions, and seismic cycling and vibration. An expansion joint control system is conventionally installed in the gap to provide a bridge across the gap and to accommodate the movements occurring in the vicinity of the gap.
Expansion joint control systems are often used in open air structures, such as stadiums. The tread and riser applications in stadiums require the expansion joint control system to accommodate multi-directional movement resulting from seismic and thermal events, while still permitting egress across the expansion joint gap in the event of an seismic or thermal event during the sporting or entertainment event.